The present invention relates to new polymers prepared from polyisocyanates and polyepoxides and a process for preparing same, as well as to their application in the manufacture of foams having good fire resistance.
It is known to prepare polymers by reacting polyisocyanates and polyepoxides to form polyoxazolidones, the process being carried out in the presence of appropriate catalysts and co-catalysts such as quaternary ammonium halides, tertiary amines, phosphonium halides and aliphatic alcohols as described in U.S. Pat. Nos. 3,020,262, 3,313,747, and 3,694,406. In order to prepare foams from these polyoxazolidones it is necessary to incorporate a pore-forming agent therein as described in U.S. Pat. Nos. 3,242,103 and 3,673,128. To reduce the friability of the foams and increase their fire resistance, it has further been proposed to manufacture same with polyoxazolidones containing isocyanurate chains in the molecule. For example, it has been proposed to prepare oxazolidone-modified isocyanurate resins by trimerizing an isocyanate terminated polyoxazolidone in the presence of a trimerization catalyst as described in U.S. Pat. No. 3,793,236. The foams obtained from such polyisocyanurates are of improved quality but their preparation from epoxide compounds and isocyanates requires the preliminary synthesis of the oxazolidone isocyanate, followed by the polymerization thereof to the isocyanurate. Moreover, the addition of a poreforming agent nevertheless remains necessary.
The entire disclosure of each of the aforementioned U.S. patents is expressly incorporated herein by reference.